Field
Embodiments of the present disclosure generally relate to apparatuses and methods for microlithography patterning and more particularly for microlithography patterning for large substrates with a photoresist film applied.
Description of the Related Art
Large area substrates are often utilized to support electrical features used in electronic devices. In some cases, large area substrates are used when manufacturing flat panels for active matrix displays such as computers, touch panel devices, personal digital assistances (PDAs), cell phones, television monitors, and the like. Generally, flat panels may comprise a layer of liquid crystal material forming pixels sandwiched between two plates. When power from the power supply is applied across the liquid crystal material during use, an amount of light passing through the liquid crystal material may be precisely controlled at pixel locations enabling images to be generated.
In some cases, microlithography techniques are employed to create electrical features incorporated as part of the liquid crystal material layer forming the pixels. According to this technique, a radiation-sensitive photoresist is applied to form a layer on a substrate surface with either a track or coater system to produce typically a sub-millimeter thickness of photoresist upon at least one surface of the substrate. In wafer microlithography often it is possible to achieve a uniform photoresist thickness of less than ten (10) nanometers of the photoresist upon a circular-shaped substrate by spinning the substrate to close to five-thousand (5,000) revolutions per minute for up to one (1) minute to distribute the photoresist across the substrate. However, in the case of large rectangular-shaped substrates, it is more difficult to achieve the same photoresist thickness uniformly across the substrate. Indeed, substrates for flat panel display manufacturing are in some cases sixteen (16) times larger than those substrates used in wafer microlithography and have a non-circular shape which makes effective spin coating of photoresist difficult. Variation in the photoresist thickness uniformity across the substrate results in variation in feature sizes of pattern features as formed in the photoresist across the substrate. This non-uniformity of feature size may negatively impact the performance of electronic devices formed by the pattern features, whether the substrate is intended to support flat panel display manufacturing or other electronic-based products.
In this regard, demand continues to increase for less expensive, larger, and higher performance electronic devices. Larger substrates with smaller and more uniform features are required to satisfy the demand for these electronic devices. New approaches are needed to more precisely create smaller and more uniform patterns on large substrates.